Reversing gear for internal combustion engines



MCRH 193% J. c. MATTHEW REVERSING GEAR FOR INTERNAL COMBUSTION ENGINESFiled April 30, 1952 wa enfoz- Patented Mar. 13, 1934 PATENT OFFEUEBEVERSING GEAR. FOR INTERNAL COMBUS- TION ENGINES John Caesar Matthew,Mosigkau in Anhalt, Germany, assignor to Germany Application April 30,

Hugo Junkers, Dessau,

1932, Serial No. 608,496

In Germany May 4, 1931 7 Claims.

My invention relates to internal combustion engines and more especiallyto such engines which are reversed by means of compressed air.

In order to prevent damage from reversible internal combustion engineswhen started or reversed by compressed air, the following mainprinciples should be observed:

(a) Compressed air for starting and fuel never should be supplied at thesame time into the 10 working chamber of the engine, since otherwiseinadmissible high pressures may occur.

(b) At all events the control of fuel supply must correspond to thedirection of rotation in which the engine is running, since otherwiseinadmissible vehement preignitions may occur.

(0) It should be possible to supply the compressed air for starting andreversing to the engine running in a given direction in a manner ofcontrol corresponding to the other direction of rotation in order tomake possible a braking action on the engine, still running in the olddirection, by means of the starting air.

Devices are known in which two different operating members (e. g.handlevers) are provided for, the one member for shifting the fuelsupply control gear, the other for shifting the starting air controlgear. In this case certain barring devices are necessary in order toprevent wrong manipulation, but these devices will complicate theapparatus and render its manipulation more difficult.

It is further known to shift both control gears (for starting supply andfor fuel supply) by a single operating member. In this case the centralposition of the operating member corresponds to stoppage of the engine,the next two positions on either side (each side corresponding to onedirection of rotation) corresponding to starting position and to normalrunning position or vice versa. However this arrangement also requiresspecial provisions adapted to prevent undesirable shifting throughstarting positions and further barring devices against prematurereversing of the fuel control gear before the engine has stopped.

According to my invention also a single operating member (e. g. shiftinghandle), is provided to which the control gears, for fuel and startingair, are connected in such a manner that its central position is thenormal running position whilst the next two positions on either side arestop positions and the two outer positions are starting positions, onefor forward and the other for reverse running. Further the fuel supplycontrol gear is performed in a manner as to automatically work properlyfor either direction of rotation, said gear either being so designed asto be used unchanged in either direction of rotation or so as to adjustitself automatically according to the occasional direction of rotation.

This device is simple in design, easy to manipulate and fool-proof.

The simple design is founded on the fact, that only a single shiftingmember without barring devices and the like is required and that for thereversing of the fuel supply control members (e. g. fuel pump or fueladmission valves) no mechanical coupling of said members with theshifting member is necessary. It is not difficult to perform a fuelsupply control gear working properly without ado in either direction ofrotation (e. g. by driving cams for the fuel supply control gear shapedsymmetrically to the dead centre position), especially for engines, thepump controlled fuel supply of which is finished before or at the innerdead centre, or for engines, the valve controlled fuel admission ofwhich extends over a part of the crank circle lying symmetrically to theinner dead center.

In engines where the fuel admission is distributed otherwise over thecrank circle, an automatic adjustment of the members (cams or the like)driving the fuel supply control members may be attained in a simple wayby connecting these driving members to a driving shaft, positivelycoupled to the crank shaft of the engine, by means of a special couplingdevice allowing these members a certain angular movement with respect tothe driving shaft. In multi-oylinder engines these cams or the like maybe fixed to a cam shaft and the latter be coupled by one single couplingdevice with a driving shaft positively connected to the crank shaft.Moreover these cams may be shaped in such a way that the resultingturning moment which the fuel supply control members will exert uponthis cam shaft comprises only resisting but not driving moments, andthus rattling of the mutual coupling device will be avoided.

The manipulation is simple, as a single operating member (lever or thelike) makes it possible to go over from any working condition of theengine to any other working condition without leaving hold of it andwithout additional manipulation of any barring devices.

Finally the utmost security is obtained against trouble in starting andreversing as the object of this invention performs the conditions (a) to(c) mentioned in the beginning without any reservation.

- versing gear, illustrated by Figs. 2 to 4 the op- In the drawingaflixed to this specification and forming part thereof, embodiments ofmy invention are illustrated diagrammatically by way of example. In thedrawing Fig. 1 is a diagram illustrating the shifting positions of theoperating member.

Fig. 2 is a front view of the reversing gear in normal running position.

Fig. 3 is a front view in a stop position,

Fig. 4 is a plan view of that gear.

Figs. 5 and 6 are showing a cross-section, on the line V--V of Fig. 6and a side elevation of a cam shaft and of its driving device foractuating the fuel supply gear of a multi-cylinder.

engine.

Fig. 7 is a front view of a specially shaped cam.

Referring to Fig. 1 I indicates the central position of the operatingmember whichin thatv case corresponds to the normal running position(fuel is admitted). This normal running position is common to bothdirections of rotation.

The next two positions II and II", on either side of the normal runningposition I, are stoppage positions (starting air and fuel are shut off).

The positions III and III, beyond the stoppage positions, are startingpositions (starting air is admitted).

In the example of embodiment of the new reerating member is representedby a lever 1 fixed to a disc 2 which is pivotally mounted on a shaft 4carried by the fixed support 3. The fuel supply to the engine iscontrolled by a pump 5 9 which is driven by a cam 6 placed on the shaft7.

This cam is shaped symmetrically and connected to the shaft '7 by meansof a coupling device consisting on the one hand of a bow shaped groove 8in the cam with the end faces 9, 10 and on the other hand of a stud 11on the shaft '7, projecting into said groove, so as to allow the cam acertain angular movement with respect to the shaft. If the shaft '7rotates in the direction of the arrow a the left side of the projection11 will lean against the left endface 9 of the groove 8 and then the cam6 is taken around with the shaft 7. If the shaft '7 is reversed the .cam6 at first is held back by the resistance of the pump until the otherside of the stud 11 reaches the end face 10 of the groove 8, then thecam.

is taken around in the reversed direction. Thus,

at'reversing the engine, the cam performsautomatically a certain angularmovement with re-, spect to the shaft 7 and consequently the controlgear of the fuel pump will work properly for both directions ofrotation.

The disc 2 has two peripheral cams 12, 13 and between them a groove 14into which, at the normal running position I, the nose end 15 of abell-crank lever 16 projects, whilst its other end 17 lies below aprojection 18 of the pump. tappet stem, however without preventing theaction of the pump, (Fig. 2). The earns 12, 13 are so shaped that, thelever 1 being shifted from position I to any other position, the nose15will.

be moved to the right, to such an extent that the end 1'7 of the leverwill lift the pump tappet stem 19 as much as toget free from the cam 6.

The gear for the starting air supply control comprises a sliding sleeve26 mounted on.v the shaft 7 unturnable with respect to it but shiftablein its axial direction. This sleeve 20 bears the cams 21 and 21", one ofthem operating the starting valve 25 at starting in the forwarddirection, the other at starting in the reverse direction. The cams haveinclined surfaces at their sides facing each other which will lift thestarting valve stem when the sleeve 20 is shifted and supposed that thevalve stem is just in the shifting way of the respective cam. Thestarting air enters the starting valve case 24 at 23 and flows throughthe pipe 26 to the working chamber as soon as the starting valve 25,which is permanent lyflloaded by a spring 27 in the sense of closing, isopened by-oneof the two cams 21' or 21. The shifting of the sleeve 20 iseffected by means of a front cam 30 which is attached to the disc 2andhas three steps 31-, 32, 33 interconnected with one another byinclined passages, and by means of a double armed lever revolvable aboutthe fixed pivot 35 one end 34 of said lever being permanently pressedagainst the cam 30 by a spring 38, the other end 36 catching in a groove37 of the sleeve 20. The middle step 32 is as long as to allow the leverend 34 to slide up to the higher step 31 or down to the lower step 33,only if the handle 1 is shifted beyond one of the two stoppage positionsII II".

The mechanism works as follows:

When the engine is at rest the. operating member (lever 1) will be inone of the two stoppage positions II or 11", for example in II (Fig. 3).The fuel pump 5 is shut off, the sleeve 20 is in its middle position,the starting valve 25 is closed. For starting the. lever 1 is shiftedinto the starting position for. the wanted direction of rotation, thatis into the adjacent startingj position III or, passing the. normalrunning position I and the other stoppage position II", into the otherstarting position III. Thereby either step31 or. 33 of the front cam 30comes to lieagainst the lever end'34, and consequently the leveris-turned roundits pivot 35 and the other end 36 of it shifts the sleeve20 so that one of thestartingcams 21' and 21" comes in line with thestem-of the starting valve 25 which consequently is opened and thusadmits starting air to the working chamber. As soon as the enginehasstarted the handle 1 is shifted backwards through, the, adjacent.stoppage positioninto the normal running position I (Fig. 2). Therebythe lever end 34 returns to the step 32 of the cam30; thus the startingair is shut off again, the nose 15 of the lever 16 enters the groove 14between the cams 12 and 13, thereby the fuel pump is set to work, thecam 6 of. which, in consequence of the arrangement of the couplingdevice, automatically is put into that position, which correspondstothechosen direction ofrotation.

For stopping, the handle 1 is shifted from the normal running position Iat will into one of the two adjacent stoppage positions II or II.".

In order to reverse the running engine the handle 1 at once is shiftedfrom the normal running position I into, ,thefstarting position of the.reversed direction of rotation (for instance III), thereby passing thestopping position IIf' between them When the starting position III) isreached the breaking action of position) theoperating member only canpass the harmless stoppage positions or, the normal running position inwhich for every direction of rotation the fuel supply control memberswill automatically adjust itself properly, but avoids passing throughundesirable starting positions or through normal running positions withadmission of fuel not corresponding to the actual direction of rotation.No manipulation of the operating member, however it may be, ill causerisk for the engine. On this account barring devices against wrongmanipulation are not necessary.

If the cams for driving the fuel pump members are connected individuallyto the control shaft by means of the above mentioned couplings thedisadvantage arises, that in pushing these members a resisting torqueacts upon the cams whilst in the backwards movement of these members inconsequence of their pressure upon the cams (for instance effected by thspring which pulls out the piston) a driving torque acts upon the camsand this torque arising alternatively in opposite directions will causea hammering action between the cam-groove faces 9, 10 and the studs 11in consequence of which undue rattling and excessive wear of thecoupling parts will occur. In multi-cylinder engines in which the fuelsupply takes place on different parts of the crank circle, animprovement of this disadvantage will be attained by fixing the cams,driving the respective fuel pumps, to a common shaft, the latter beingconnected to the crank shaft by means of only one above describedcoupling device. Consequently resisting and driving torques will actmore or less synchronically on the different but rigidly interconnectedcams and therefore the driving torques will be neutralized at least to acertain amount.

Such a fuel supply control gear is illustrated in Figs. 5 and 6. Severalcams 40, displaced against each other in angular direction, are fixed tothe cormnon shaft 41 which is connected by means of the aforesaidcoupling to the driving shaft 42. The coupling consists of a disc 43with a sectorlike groove, fixed to the driving shaft 42, and of a crankpin 46 fixed to the disc 47 of the cam shaft 41. This pin 46 projectinginto the groove of the disc 43 has a certain angular play between theend faces 44, 45 of the groove. Thus the shaft 41 is enabled to performthe angular movement with respect to the shaft 42 necessary forreversing.

The disturbances, caused by the driving torques may be completelyovercome in devices where the fuel supply is controlled by pumps. Thispossibility is based on the fact, that it is admissible to place thesuction stroke of the pump piston at a convenient part of the crankcircle, not needed by the pressure stroke. Regarding this the top ofevery cam is elongated between the rising surface m and the descendingsurface n, as shown in Fig. '7, and this elongated top 2" extends overan angle 6 of such an amount, that the driving forces exerted upon thedescending surface of one cam will be effective quite synchronicallywith the greater resisting forces acting on the rising surface ofanother cam; thus the first named forces will be compensated in everyposition of the cam shaft. In consequence thereof a constant touchbetween the driving and driven members of the coupling is guaranteed.

Various changes may be made in the details disclosed in the foregoingspecification without departing from the invention or sacrificing theadvantages thereof.

In the claims affixed to this specification no selection of anyparticular modification of the invention is intended to the exclusion ofother modifications thereof and the right to subsequently make claim toany modification not covered by these claims is expressly reserved.

I claim:

1. In a reversing gear for internal combustion engines, in combination,means for supplying fuel to the engine, mechanism for operating saidfuelsupplying means, means for automatically moving said mechanism intothe position corresponding to the direction of rotation imparted to theengine, a valve for admitting starting air, valve gear for operatingsaid valve, means for placing said valve gear in two active positionsand one inactive position with respect to said valve, means for throwingout said fuel-supplying means when said valve gear is in its activeposition, and a controlling lever for operating said valve gear and saidthrowing-out means.

2. In a reversing gear for internal combustion engines in combination,means for supplying fuel to the engine, a cam for operating saidfuel-supplying means, means for automatically moving said cam into theposition corresponding to the direction of rotation imparted to theengine, a valve for admitting starting air, valve gear for operatingsaid valve, means for placing said valve gear in two active positionsand one inactive position with respect to said valve,.means for throwingout said fuelsupplying means when said.

valve gear is in its active position, and a con trolling lever foroperating said valve gear and said throwing-out means.

3. In a reversing gear for internal combustion engines in combination,means for supplying fuel to the engine, a shaft operatively connected tothe engine so as to rotate in opposite directions as the engine isreversed, a cam on said shaft adapted to operate said fuel-supplyingmeans, clutching means intermediate said cam and said shaft which meanspermit rotation of the shaft through a given angle with respect to thecam, a valve for admitting starting air, valve gear for operating saidvalve, means for placing said valve gear in two active positions and oneinactive position with respect to said valve, means for throwing outsaid fuel-supplying means when said valve gear is in its activeposition, and a controlling lever for operating said valve gear and saidthrowing-out means.

4. In a reversing gear for multi-cylinder internal combustion engines incombination, means for supplying fuel to the engine, a shaft operativelyconnected to the engine so as to rotate in opposite directions as theengine is reversed, a cam shaft having a cam per combustion chamber' inthe cylinders of said engine for operating said fuel-supplying means,clutching means intermediate said shafts which clutching means 1 permitrotation of the first-mentioned shaft through a given angle with respectto said cam shaft, a valve for admitting starting air, valve gear foroperating said valve, means for placing said valve gear in two activepositions and one inactive position with respect to said valve, meansfor throwing out said fuel-supplying means when said valve gear is inits active position, and a controlling lever for operating said valvegear and said throwing-out means.

5. In a reversing gear for multi-cylinder internal combustion engines incombination, means for supplying fuel to the engine, a shaft operativelyconnected to the engine so as to rotate in opposite directions as theengine is reversed, a

cam shaft having a camper cylinderof theie'ngine for operating saidfuel-supplying eansthe' cams on said shaft being so designe'd that the"action which the forces resulting mm the operation of said fuel'supplying means exert on one of said cams, is balanced by the action ofsaid forces on another cam, clutching means inand's'aid throwing-outmeans. g

6. In a reversing gear for internal combustion engines in combination,means for supplyingfu el to the'engin'e, mechanism for operatingsaid-fuel supplying means, means for automatically moving saidmechanism'into the position correspond ing to'the direction of rotationimparted to the engine, a valve for admitting starting air, valve gearfor operating said valve comprising a pair of cams for alternatelyoperating'said valve, a

controlling lever, means operatively connected to said lever forselectively presenting one of said" cams at a time'to, and for placingboth cams in inactive position with respect to, said valve, andi sielg,Qi 'a v y q'n' ed' t said lever forthrpwihg-out s'aid fuel-supplyingmeans in the positionof; saidleve'r which corresponds to the activeposition of-said cams.

7 lust-reversing gear for'int'ernal' combustionenginesinfcombinaticnfmeans for supplying fuel to thfeflengine;mechanismfor operating said fuels upplying-means, means forautomatically movirig" said'rnechanism into the position correspondm t9the ,di ec qn of rretai im t to the engine; valvelfqr admitting startingair, valve gear for operatin gsaid valve, comprising a'pair of Canasforaiterriately' operating said valve, a controlling lever, a cam plateoperatively connected to said lever, a set of; camr ning members on saidc'arii plate, meansj operatively connected to said (jamming membersfoselectively presenting one of saidcams ata timeto, and for placing bothcams i ri inactive" position vvith respect to, said valve, another set 0f cainming members' on said' valve plate', and mean or throwing outsaidfuelsupply-ing meansop e'ratively connected to said last m'entioned;camming" members; Which lastmeiition'ed camming members are sopositioned with respect to" the first-mentioned camming members thatsaid fuel supplying means are thrown out when oneof said camsispresented to-s'a'id-valv'e; and throvvn inwhen said'ca'ms are in-theirinactive position.

JOHN CAESAR MATTHEW.

